What's the difference (other than color) between Weyerman CaraAroma and Dingemans Aromatic?

Well, technically you can use the Dingemans up to 100%, albeit with relatively low diastatic power — and it probably has similar caramel notes to the CaraAroma. But given the vast °L difference between the two, I think CaraAroma (IMO) has a richer, deeper caramel aroma contribution...but that's subjective and depends upon how much you're using I imagine.

I'd think that you'd want to use the CaraAroma for bigger, darker beers over the Dingemans, which you might use for less-darker beers but want that deep caramel aroma. Just my two cents, and quite obviously subjective.

CaraAroma and Aromatic aren't really very similar grains. The first is a crystal malt that gives Dark Munich Malt-like flavors, while the second is a toasted malt similar to an exaggerated Light Munich Malt.